--- a/content/media/ogg/nsOggReader.cpp
+++ b/content/media/ogg/nsOggReader.cpp
@@ -1324,24 +1324,24 @@ nsresult nsOggReader::SeekBisection(PRIn
         if (codecState && codecState->mActive) {
           int ret = ogg_stream_pagein(&codecState->mState, &page);
           NS_ENSURE_TRUE(ret == 0, NS_ERROR_FAILURE);
         }
 
         ogg_int64_t granulepos = ogg_page_granulepos(&page);
 
         if (HasAudio() &&
-            granulepos != -1 &&
+            granulepos > 0 &&
             serial == mVorbisState->mSerial &&
             audioTime == -1) {
           audioTime = mVorbisState->Time(granulepos);
         }
         
         if (HasVideo() &&
-            granulepos != -1 &&
+            granulepos > 0 &&
             serial == mTheoraState->mSerial &&
             videoTime == -1) {
           videoTime = mTheoraState->StartTime(granulepos);
         }
 
         if (mPageOffset == endOffset) {
           // Hit end of readable data.
           break;